Windows form - Label

[fayazmd]

Hi,

I am stuck with a problem on labels. I have 30 labels on my from. And from one method i am returning a value, based on it i have to make one label as invisible.

I took switch - case, but i am guided to take object of that label and make it invisible.

I followed this code, but it is throwing error.

Label ToHide = new Label();
ToHide = Convert.ChangeType("Label"+ind, TypeCode.Object);
(ToHide as Label).Visible = false;

Here ind is int returning from one method, and i am concatinating it to get label name.

[Plater]

You would need to get the instance of that control first and not just create a new label.
Try something like:

Label ToHide;
ToHide =this.Controls.Find("Label" + ind, true);
if(ToHide!=null)
{//it found your label
   (ToHide as Label).Visible = false;
}
 

[fayazmd]

Thanks for your reply.
I am sorry, I forgot to mention. I am working in .net 2003.
Where i couldn't find 'this.Controls.Find'. Please suggest me how can i proceed.

You would need to get the instance of that control first and not just create a new label.
Try something like:

Label ToHide;
ToHide =this.Controls.Find("Label" + ind, true);
if(ToHide!=null)
{//it found your label
   (ToHide as Label).Visible = false;
}
 

[jjvainav]

Here is another way you can do this without using the Controls.Find method:

string labelToHide = "Label" + ind;
if(this.Controls.ContainsKey(labelToHide))
{
    this.Controls[labelToHide].Visible = false;
}
 

A word of caution, the this.Controls.ContainsKey method does not do a recursive search like the Controls.Find method does. So if your labels are added to a container, such as a panel, then the this.Controls.ContainsKey method will return false.

Hi,

I am stuck with a problem on labels. I have 30 labels on my from. And from one method i am returning a value, based on it i have to make one label as invisible.

I took switch - case, but i am guided to take object of that label and make it invisible.

I followed this code, but it is throwing error.

Label ToHide = new Label();
ToHide = Convert.ChangeType("Label"+ind, TypeCode.Object);
(ToHide as Label).Visible = false;

Here ind is int returning from one method, and i am concatinating it to get label name.

[Plater]

Then I guess you will need to make a mimic of this function:

private Control Find(Control startpoint, string ControlName, bool Recurse)
{
    foreach (Control c in startpoint.Controls)
    {
      if (c.Name == ControlName)
      {
          return c;
      }
      if ((Recurse) & (c.HasChildren))
      {
        Control temp=Find(c, ControlName, Recurse);
        if (temp != null)
        {
          return temp;
        }
      }
    }
return null;
}
 

Then you can use it like:

Control myc=Find(this,"Label"+ind,true);
if(myc!=null)
{//found the control
}
 

[fayazmd]

Thanks, it's working.

Then I guess you will need to make a mimic of this function:

private Control Find(Control startpoint, string ControlName, bool Recurse)
{
    foreach (Control c in startpoint.Controls)
    {
      if (c.Name == ControlName)
      {
          return c;
      }
      if ((Recurse) & (c.HasChildren))
      {
        Control temp=Find(c, ControlName, Recurse);
        if (temp != null)
        {
          return temp;
        }
      }
    }
return null;
}
 

Then you can use it like:

Control myc=Find(this,"Label"+ind,true);
if(myc!=null)
{//found the control
}
 

[fayazmd]

Hi Plater,

Nice method. It replaced my lines of coding to few lines.

I understood the method that you are looking for each control and control's name against all controls in your form. But, i didn't get recurse and has children part. This block of code

if ((Recurse) & (c.HasChildren))
{
Control temp=Find(c, ControlName, Recurse);
if (temp != null)
{
return temp;
}
}

Could you please explain me this block. Thanks in advance.

Then I guess you will need to make a mimic of this function:

private Control Find(Control startpoint, string ControlName, bool Recurse)
{
    foreach (Control c in startpoint.Controls)
    {
      if (c.Name == ControlName)
      {
          return c;
      }
      if ((Recurse) & (c.HasChildren))
      {
        Control temp=Find(c, ControlName, Recurse);
        if (temp != null)
        {
          return temp;
        }
      }
    }
return null;
}
 

Then you can use it like:

Control myc=Find(this,"Label"+ind,true);
if(myc!=null)
{//found the control
}
 

[Plater]

The reason you have to check for children is that the Controls is really a "tree" heirarchy.
Say you have a form called Form1
Then you add a Texbox tb1 and a groupbox gb1.
In the group box you stick two labels lb1 and lb2

Form1.Controls will contain:
tb1
gb1

gb1 will "HasChildren"
and gb1.Controls will contain
lb1
lb2

So just searching in Form1.Controls will not contain child controls of it's children.
Therefor I recurse(if you set the boolean to true) through the children to look for other children to see if it's a match.

[fayazmd]

Thank you once again for explanation.

The reason you have to check for children is that the Controls is really a "tree" heirarchy.
Say you have a form called Form1
Then you add a Texbox tb1 and a groupbox gb1.
In the group box you stick two labels lb1 and lb2

Form1.Controls will contain:
tb1
gb1

gb1 will "HasChildren"
and gb1.Controls will contain
lb1
lb2

So just searching in Form1.Controls will not contain child controls of it's children.
Therefor I recurse(if you set the boolean to true) through the children to look for other children to see if it's a match.